Powering I/O Circuits With The Auxiliary Supply - Automation Direct Terminator Installation And I/O Manual

Chapter 3: I/O Wiring and Specifications
In some cases, using the built-in auxiliary +24VDC supply can result in a cost savings for
your control system. It can power combined loads up to 500mA if power budget allows. Be
1
careful not to exceed the current rating of the supply. If you are the system designer for your
application, you may be able to select and design in field devices which can use the +24VDC
2
auxiliary supply.

Powering I/O Circuits with the Auxiliary Supply

3
All AC power supplies feature an internal auxiliary supply. If input devices AND output loads
need +24VDC power, the auxiliary supply may be able to power both circuits as shown in the
4
following diagram.
5
6
7
8
9
10
DC-powered units are designed for application environments in which low-voltage DC
11
power is more readily available than AC. These include a wide range of battery-powered
applications, such as remotely-located control, in vehicles, portable machines, etc. For this
type of application, all input devices and output loads typically use the same DC power source.
12
Typical wiring for DC-powered applications is shown in the following diagram.
13
14
A
B
C
D
3-4 Terminator Installation and I/O Manual, 3rd Edition, Rev. B
AC Power
Power Input
Terminator I/O System
Auxiliary
Input Module
+24 VDC
Supply Inputs
–
+
+
+
DC Power
– –
Terminator I/O System
Power Input
Input Module
Inputs
Output Module
Com. Outputs Com.
Loads
Output Module
Com. Outputs Com.
Loads